Dry powder inhalers (DPIs) represent a promising alternative to pressurized pMDI (pressurized metered dose inhaler) devices for delivering drug aerosols without using CFC propellants. See generally, Crowder et al., 2001: an Odyssey in Inhaler Formulation and Design, Pharmaceutical Technology, pp. 99-113, July 2001; and Peart et al., New Developments in Dry Powder Inhaler Technology, American Pharmaceutical Review, Vol. 4, n. 3, pp. 37-45 (2001). Typically, the DPIs are configured to deliver a powdered drug or drug mixture that includes an excipient and/or other ingredients.
Generally described, known single and multiple dose dry powder DPI devices use: (a) individual pre-measured doses in blisters containing the drug, which can be inserted into the device prior to dispensing; or (b) bulk powder reservoirs which are configured to administer successive quantities of the drug to the patient via a dispensing chamber which dispenses the proper dose. See generally Prime et al., Review of Dry Powder Inhalers, 26 Adv. Drug Delivery Rev., pp. 51-58 (1997); and Hickey et al., A new millennium for inhaler technology, 21 Pharm. Tech., n. 6, pp. 116-125 (1997).
In operation, DPI devices strive to administer a uniform aerosol dispersion amount in a desired physical form of the dry powder (such as a particulate size) into a patient's airway and direct it to a desired deposit site(s).
A number of obstacles can undesirably impact the performance of the DPI. For example, the small size of the inhalable particles in the dry powder drug mixture can subject them to forces of agglomeration and/or cohesion (certain types of dry powders are susceptible to agglomeration, which is typically caused by particles of the drug adhering together), which can result in poor flow and non-uniform dispersion. In addition, as noted above, many dry powder formulations employ larger excipient particles to promote flow properties of the drug. However, separation of the drug from the excipient, as well as the presence of agglomeration, can require additional inspiratory effort, which, again, can impact the stable dispersion of the powder within the air stream of the patient. Unstable dispersions may inhibit the drug from reaching its preferred deposit/destination site and can prematurely deposit undue amounts of the drug elsewhere.
Further, some dry powder inhalers can retain a significant amount of the drug within the device, which can be especially problematic over time.
Some inhalation devices have attempted to resolve problems attendant with conventional passive inhalers. For example, U.S. Pat. No. 5,655,523 proposes a dry powder inhalation device which has a deagglomeration/aerosolization plunger rod or biased hammer and solenoid, and U.S. Pat. No. 3,948,264 proposes the use of a battery-powered solenoid buzzer to vibrate the capsule to effectuate the release of the powder contained therein. These devices propose to facilitate the release of the dry powder by the use of energy input independent of patient respiratory effort. U.S. Pat. No. 6,029,663 to Eisele et al. proposes a dry powder inhaler delivery system with a rotatable carrier disk having a blister shell sealed by a shear layer that uses an actuator that tears away the shear layer to release the powder drug contents. U.S. Pat. No. 5,533,502 to Piper proposes a powder inhaler using patient inspiratory efforts for generating a respirable aerosol and also includes a rotatable cartridge holding the depressed wells or blisters defining the medicament-holding receptacles. A spring-loaded carriage compresses the blister against conduits with sharp edges that puncture the blister to release the medication that is then entrained in air drawn in from the air inlet conduit so that aerosolized medication is emitted from the aerosol outlet conduit. U.S. Pat. No. 6,971,383 to Hickey et al. and U.S. Pat. No. 6,889,690 to Crowder et al. describe using custom signals matched to a particular dry powder to facilitate fluidic delivery. The contents of all of these patents are hereby incorporated by reference as if stated in full herein.
Notwithstanding the above, there remains a need for alternative inhalers and/or drug containment devices that can be used to deliver dry powder medicaments.